Electron beam deflection apparatus

ABSTRACT

Apparatus for deflecting the beam of an electron beam welding device, or similar source of a beam of radiant energy. The apparatus comprises a sine/cosine wave generator and a triangular/rectangular wave generator selectively connectable to the inputs of a bi-channel amplifier whose output is connected, for example, to the deflection coils, or plates, of the electron beam device. Circuitry is provided to obtain either a frequency or amplitude modulation of the deflection currents or voltages supplied to the deflection coils or plates of the device.

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United States Patent [151 3,674,977 Mayer et al. 1 July 4, 1972 [54]ELECTRON BEAM DEFLECTION [56] References Cited APPARATUS UNITED STATESPATENTS Inventors: Rolf Mayer; Johann Reitinger, both of 3,393,3707/1968 Bauer ..2l9/l2lEBX Stuttgart, Germany 3,543,286 11/1970 Stentz etal. ..219/121 EB 3,491,236 1/1970 Newberry.... ..219/121 EM X Asslgneeiumvmms'ut'gam "Presented by 3,390,222 6/1968 Anderson ..219/121 EB xInstitut fur Kernenergetik, Stuttgart, Gery Irimary Examiner.|. V. TruheAssistant Examiner-Gale R. Peterson Filed: Dec. n, 1970 Attorney-Kelmanand Berman Appl. No.2 97,095

Foreign Application Priority Data 57 ABSTRACT Apparatus for deflectingthe beam of an electron beam welding device, or similar source of a beamof radiant energy. The apparatus comprises a sine/cosine wave generatorand a trian- Dec. 18, 1969 Germany ..P 19 63 454.9 gular/rectangularwave generator selectively connectable to the inputs of a bi-channelamplifier whose output is con- US. Cl. ..219/121 EB nected, for p to thedeflection coils, 0r p of he 1nt.Cl ..B23k /00 electron beam deviw-Circuitry is Provided to 99min either a new of Search "219/121 EB 121 EA121 frequency or amplitude modulation of the deflection currents 2'50/49or voltages supplied to the deflection coils or plates of the device.

7 Claims, 5 Drawing Figures o-c Amp/Made V V 7 (Onl/o/fir lg Amp/[her 73N l 1, or 1.9 Sine/Cosine unccl'on 57? g Generator 39/9110" Z Z I ID/anyu/ar/ l'u D C K10 Aez/gafveyular N 7 V0 ayg dmp/fflbr GeneratorSource 2 P'ATENTEDJUL 4 1912 saw 10F 5 Inventors MW? a V MM 3.674.977SHEET 2 BF 5 PATENTEnJuL "4 m2 m 1 3 M M 3. NM

PATENTEDJUL 4 I972 SHEEI 3 BF 5 iii WiimiiPi]! Inventors Rolf Mayer;Johann Kedz' ffi E y: W 4 W fiwzww BACKGROUND OF THE INVENTION 1. Fieldof the Invention Broadly speaking, this invention relates to deflectiongenerators. More particularly, in a preferred embodiment, this inventionrelates to a deflection generator for deflecting a beam of radiantenergy along a plurality of predetermined trajectories. The invention isparticularly suited for deflecting the beam of an electron beam weldingapparatus with respect to the workpiece to be welded.

2. Discussion of the Prior Art The vast majority of bonding interfacesfound in industry are, because of production problems, relatively simplecurves, such as straight lines, circles, ellipses, etc. or curves madeup from elements of the listed basic curves. When bonding suchinterfaces by means of an electron beam apparatus, for example, it is,of course, necessary to move the electron beam, relative to theworkpiece, so that the focused electron beam traverses the desired curvedefined by the bonding interface.

One way to do this to to place'the workpiece on a table, which isadopted for translation in the X-Y plane, beneath the focused electronbeam. The table is then displaced manually, or automatically, whilevisual inspection of the weldment is continuously made. Unfortunately,this technique works well for only the more simple curves and, in anyevent, is not suitable for large scale production.

Because a focused electron beam has a relatively narrow cross-section,it is known in the art to wobble" the electron beam from side to side,in order to provide some heating or melting of areas immediatelyadjacent the bonding interface. In the prior art, such a wobble has beenprovided by applying the A. C. mains to the electron beam deflectingcoils via a suitable potentiometer. Unfortunately, the frequency of theAC. mains (50 to 60 H2) is too low for this application and it hasproven necessary to move the XY table from side to side if this highlyadvantageous supplementary heating is desired.

It has been proposed in the past to use conventional L-C and R-Coscillators of higher frequency to provide this highly desirable beamwobble and/or to deflect an electron beam in a circular or ellipticaltrajectory or any combination thereof. Unfortunately, the results whichhave been obtained with these conventional oscillators have not beensatisfactory, due to the relatively high harmonic and phase distortionpresent in the output signal. Further, these prior art oscillatorsexhibit an undesirable inter-relationship between frequency andamplitude such that a two-dimensional representation of the desiredcurves is impossible, with the accuracy required for the welding. Theprior art oscillators are also unable to provide stable output signalsat a frequency low enough to satisfy the requirements of a largeelectron beam welding apparatus. I

The problem, then, is to find a deflection generator for an electronbeam apparatus, or other radiant energy source, which will generatedeflection currents (or voltages) to cause the electron beam to traversecircular or elliptical trajectories or any combination thereof, withminimal error and distorfion. The generator should also be capable ofwobbling the beam either along, or transverse to, the trajectory andshould be capable of operating over an extremely wide frequency band,without sacrificing the low distortion qualities of the deflectioncurrent, or voltage.

SUMMARY OF THE INVENTION This problem has been solved by the instantinvention which, in a preferred embodiment comprises at least onegenerator for generating at least one output signal of a predeterminedand stabilized amplitude, frequency and phase; a stabilized, bi-channeloutput amplifier; deflection apparatus, connected to the output of thestabilized output amplifier; and circuitry, connecting the output signalor signals to the input of the bi-channel amplifier, so that anamplified replica of the output signal or signals is impressed acrossthe deflection apparatus to controllably deflect the radiant energybeam.

2 DESCRIPTION or THE DRAWINGS FIG. 1 is a block diagram of an generatoraccording to this invention;

FIG. 2 is a schematic drawing of an illustrative sine/cosine generatorfor use with the deflection generator of FIG. 1;

FIG. 3 is a schematic drawing of an illustrative triangular/rectangularwave generator for use with the deflection generator of FIG. 1;

FIG. 4 is a schematic drawing of an illustrative frequency modulatingcircuit for use with the sine/cosine generator of FIG. 2; and

FIG. 5 is a schematic drawing of an illustrative amplitude modulatingcircuit for use with the sine/cosine generator of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a block diagram of anillustrative deflection generator, according to the invention. Oneskilled in the art will appreciate that the generator shown is equallysuited for electrostatic as well as electromagnetic deflection. As shownin FIG. 1, the deflection generator comprises two individual generators;a sine/cosine generator 1 and a triangular/rectangular wave generator 5.The Sine/cosine generator I is connected to an amplitude controller 2and has two output connections 3 and 4 on which the sine wave and cosinewave signals appear, respectively. In similar fashion,triagular/rectangular wave generator 5 has two output connections 6 and7 on which the triangular wave and rectangular wave signals appear,respectively. The outputs of generators l and 5 are connected to afunction selector 8 which selects the desired waveform, under control ofan operator, and passes it to one input 9, 10 of a pair of outputamplifiers l1 and 12, respectively. The current stabilized outputs ofoutput amplifiers l1 and 12 are connected, in turn, to a pair ofdeflection coils l3 and 14, respectively, which are associated with theelectron beam apparatus (not shown since it is conventional). One sideof deflection coil 13 and 14 is connected to ground, via a shuntresistor 15 and 16, respectively. A limit indicating circuit 18 isconnected to the outputs of the two output amplifiers, l1 and 12, and toa warning indicator bulb I9 so that when the output voltage of eitheramplifier reaches some predeten'nined value, the limit indicatingcircuit lights the warning lamp.

A pair of adjustable d. c. voltage sources 22 and 23 are connected tooutput amplifiers l l and 12, respectively, to permit the operator toadjust the position of the electron beam on the workpiece, in the sameway that the trace of an oscilloscope can be centered on the scopescreen.

Turning now to FIG. 2, sine/cosine generator 1 comprises a pair ofserially connected operational amplifiers 30 and 31, which function asintegrating circuits. A third operational amplifier 32, acu'ng as aninverting stage, is connected in the feedback path which interconnectsthe output of operational amplifier 31 and the input of operationalamplifier 30. This configuration represents a self-oscillating systemwith the result that a sinewave signal appears at the output 3 ofoperational amplifier 30 while a signal delayed by IT/2, or a cosinewave, appears at the output 4 of operational amplifier 31. The frequencyat which the system oscillates is determined by the parameters of a pairof load resistors 33 and 34, the value of a plurality of capacitors35-43 and 36-44 and by a pair of voltage dividers 45 and 46 in thefeedback paths associated with operational amplifiers 30 and 31,respectively.

Capacitors 35, 37, 39, 41 and 43 and capacitors 36, 38, 40, 42 and 44are of paired, equal values and are, advantageously, arranged in decadeincrements. A ganged stepping switch 47 can connect a corresponding pairof capacitors to the respective feedback loop. Thus, if the capacitorsincrease in decade fashion, rotation of switch 47 will result in tenfoldchanges in frequency of the system. The two voltage dividers 45 and 46are of equal value and are advantageously fonned from a ganged pair ofpotentiometers. Voltage dividers 45 and 46 serve to provide a continuousfrequency adjustment, within any given decade.

illustrative deflection Oscillations are initiated in the system bytemporarily connecting the output 56 of operational amplifier 32 to theinput 48 of operational amplifier 31. To obtain stable oscillations ofconstant amplitude a well defined feedback coefficient is required,which is, of course, provided by the amplitude controller 2 (FIG. 1). 1

Rapid build-up of the amplitude of the oscillations in the circuit maybe obtained if, shortly after the apparatus is turned on, and,therefore, shortly after the supply voltage is applied to power supplyterminal 49, capacitor 37, for example, associated with one of thefeedback loops is charged to a voltage which is determined by a thirdvoltage divider 50 which is connected to the power supply terminal 49.

The circuit further comprises a transistor 53 whose emitter is connectedto ground and whose base is connected to the midpoint of a capacitor 51and a resistor 52 serially connected between ground and the powersource. After the supply voltage is tumed on, capacitor 51 chargesthrough resistor 52. Thus, the base of transistor 53 becomes positivefor a time period determined primarily by the time-constant of resistor52 and capacitor 51. During the interval when the base of transistor 53is positive, the transistor is biassed on and a relay 54 in thecollector circuit thereof is operated. Relay 54, operated, provides thedesired path between voltage divider 50 and capacitor 37, say, for fastwarm-up. When capacitor 51 becomes fully charged, transistor 53 turnsoff, releasing relay 54 and breaking the path from voltage divider50 tocapacitor 37.

FIG. 3 depicts the schematic of an illustrative triangular/rectangularwave generator 5. As shown, the generator comprises the serialconnection of an inverting, integrating stage 60, a hysteresis switchingstage 62, a pulse-shaping stage 63, a wave-shaping stage 64, and asymmetrical output stage 65.

The inverting, integrating stage 60 includes an operational amplifier 61which serves to integrate any d. c. voltage applied thereto (e.g., anegative d.c. potential) and thus produces at its output terminal 66 asteadily increasing ramp potential of opposite polarity. The rampvoltage appearing on terminal 66 is also fed to the input of thehysteresis switch stage 62.

This latter stage includes a pair of interconnected transistors 67 and68 which interchange their normally conducting and non-conducting stateswhen the input voltage (from output 66 of stage 60) reaches somepredetermined level. The signal which is produced when hysteresis switch62 changes state is shaped by pulse-shaping stage 63, renderedsymmetrical by wave-shaping stage 64 and amplified by output stage 65.The amplified signal is fed back over a feed-back loop to the input ofintegrating stage 60 as a positive signal. This, in turn, generates asteadily decreasing ramp voltage at output terminal 66, starting withthe final value reached at the instant that hysteresis switch 62 changesstate.

The decreasing ramp voltage at terminal 66 is fed, as before, to thehysteresis switch 62 and when a predetermined negative limit is reached,the transistors 67 and 68 again change state, and the process repeats adinf'mitum. Thus, the output voltage which appears across terminal 66, asa function of time, will assume a triangular waveform. Correspondingly,the waveform which will appear across the output 69, of the symmetricaloutput stage 65, will reflect the state of the hysteresis switch andwill, thus, be a rectangular wave of the same frequency as thetriangular wave.

A variable resistor 70 connected in the supply path from batteryterminal 82 to the transistors 67 and 68 controls the thresholdswitching voltage of switch 62. A resistor 71 of negative temperaturecoefiicient, in the same path, compensates for temperature current-driftin transistor 67. A pair of Zener diodes 72 and 73, in the output ofamplifier stage 65, ensure the symmetry of the rectangular output wave,relative to ground, as well as its amplitude stability.

Because of the symmetry and stability of the rectangular output wave,integrating stage 60 produces a triangular wave at output 66 which isalso symmetrical with respect to ground. Furthermore, both waves areextremely stable in frequency as the rise time of the triangular wavedepends directly on the amplitude of the rectangular wave.

The frequency at which generator 5 oscillates is determined by thevalues of capacitors 72 to 76 in the feedback loop of operationalamplifier 61, as well as on a charging resistor 77 and a pair ofpotentiometers 78 and 79 which are connected to the input and output,respectively, of operational amplifier 61.

As before, capacitors 72 to 76 advantageously increase in value indecade fashion and are inserted into the feedback loop by a steppingswitch 80. Thus, rotation of switch 80 will change the frequency ofoscillation by powers of 10. Advantageously, potentiometer 78 may beused to adjust the frequency within any given decade, whilepotentiometer 79 may be used to provide a continuous adjustment of theamplitude of the triangular and rectangular output waves. D.C. supplypotentials of equal but opposite polarity, with respect to ground, areconnected to power supply terminals 81 81 (+ve) and 82 82 (-ve).

FIG. 4 illustrates an additional embodiment of the invention which maybe used when it is desired to superimpose some frequency modulation onthe sine and cosine waves produced by generator 1 (FIG. 2). As shown,potentiometers 45 and 46 of FIG. 2 are replaced by a pair of analogmultiplying stages and 91, respectively.

Thus, one input to analog multiplying stage 90 comprises the output 56of the immediately preceeding operational amplifier and thecorresponding output of multiplying stage 90 is connected to loadresistor 33. In like manner, multiplying stage 91 interconnects output57 and load resistor 34.

The other input of both amplifying stages 90 and 91 is connected, incommon, to the output of an additional operational amplifier 92, whichfunctions as an adder stage. One input to operational amplifier 92 isconnected through a potentiometer 93 to a dc. source, while at least oneother input 94 is connected to the source of the modulating signal.Potentiometer 93 is used to select the basic frequency of thesine/cosine generator (FIG. 2), preferably within one of the decades.Thus, application of a modulating voltage to terminal 94 will modulatethe sinusoidal or co-sinusoidal current in the electron-beam deflectioncoils, resulting in a corresponding modulation of the circulartrajectory of the electron beam on the surface of the workpiece. In anextreme case, this modulation can reverse the motion of the beam alongthe trajectory. Such a wobble in the beam path along the weldinginterface can considerably improve the strength and quality of theweldment. The apparatus of FIG. 4 may, of course, be associated with thetriangular/rectangular wave generator of FIG. 3 by replacing, forexample, potentiometer 78 therein. I

FIG. 5 depicts yet another embodiment of the invention which may be usedif amplitude rather than frequency modulation is desired. Amplitudemodulation of the output signals from the sine/cosine generator willresult in a corresponding modulation in the radius of the circle tracedby the electron beam on the workpiece, for example.

As shown in FIG. 5, the sine and cosine outputs from generator 1 (FIG.2) on terminals 3 and 4 are applied to input temiinals 9 and 10 ofoutput amplifiers l1 and 12 (FIG. 1), respectively. The signals onterminals 3 and 4 are applied to amplifiers 11 and 12 through a pair ofequal value resistors and 101, respectively, and also to one input of apair of analog multiplying stages 102 and 103, respectively.

The outputs of multiplying stages 102 and 103 are connected by a secondpair of equal value resistors 104 and 105, to the inputs 9 and 10 ofamplifiers l1 and 12, respectively. The outer inputs 106 and 107 tomultiplying stages 102 and 103, respectively, are connected, in common,to the source of modulating voltage, advantageously a completelyseperate generator. Resistors 100 and 104 and 101 and sum whateverinputs are connected thereto. Thus the output of amplifier 11, forexample, is the sum of the sine wave on terminal 3 together with theproduct of the sine wave on terminal 3 and the modulating voltage. Thenet effect is to vary the amplitude of the sine wave output fromamplifier 11 by the modulating voltage. The apparatus of FIG. 5 may alsobe utilized with the triangular/rectangular wave generator of FIG. 3 byconnecting terminals 6 and 7 thereto, rather than terminals 3 and 4shown in FIG. 5.

The above description of a preferred embodiment of the invention is setin the context of electromagnetic deflection of an electron beammachine. One skilled in the art will appreciate that only minor changesare necessary to use the invention with an electrostatically deflectedelectron beam machine. It will, likewise, be apparent that the inventionis not limited in any way to the deflection of an electron beam, but,with appropriate minor modifications, could be used equally well todeflect a light beam, a sound beam or a beam of gamma particles, etc.

What is claimed is:

1. Apparatus for controllably deflecting a radiant energy beam, whichcomprises:

' a stabilized, bi-channel output amplifier;

a pair of orthogonally oriented electromagnetic deflection coils fordeflecting said beam, said coils being connected to the respectiveoutput tenninal of said bi-channel amplifier; and

at least one generator having its output terminal connected to the inputterminal of said bi-channel amplifier, said at least one generatorincluding:

a first operational amplifier;

a first integrator comprising a second operational amplifier, a firstplurality of capacitors and first switching means for selectivelyconnecting one of said first plurality of capacitors as a feedbackconnection from the output of said second operational amplifier to theinput thereof;

a second integrator comprising a third operational amplifier, a secondplurality of capacitors and second switching means, ganged mechanicallyto said first switching means, for selectively connecting one of saidsecond plurality of capacitors as a feedback connection from the outputof said third operational amplifier to the input thereof;

a first voltage divider connected between the output of said firstoperational amplifier and ground, the center tap of said voltage dividerbeing connected to the input of said first integrator;

a second voltage divider, mechanically ganged to said first voltagedivider, connected between the output of said first integrator andground, the center tap of said second voltage divider being connected tothe input of said second integrator;

means for connecting the output of said second integrator to the inputof said first operational amplifier to form a closed, oscillatory loop,coarse adjustment of the frequency of oscillation thereof being efiectedby said first and second switching means, and fine adjustment thereof bysaid first and second voltage dividers, the output signal of said atleast one generator having a sinusoidal wave form and deriving from theoutput of said first integrator, the output of said second integratoryielding a second output signal, co-sinusoidal in wave form.

2. The deflecting apparatus according to claim 1, further comprising:

a resistor and a capacitor, serially connected between ground and thed.c. supply for said generator, to form an R-C timing circuit;

a transistor in common emitter configuration with its emitter connectedto ground, its collector connected to said d.c. source, and its baseconnected to the juncture of said resistor and said capacitor;

in third voltage divider connected between said d.c. source and ground;and

a relay having its annature connected in the collector circuit of saidtransistor and a nonnally open pair of relay contacts connecting thecenter tap of said third voltage divider to the particular one of saidfirst plurality of capacitors selected by said first switching means,whereby as said serially connected capacitor charges through saidresistor, 'said transistor is biassed into conduction thereby operatingsaid relay and charging said selected capacitor through said pair ofrelay contacts. 3. Apparatus for controllably deflecting a radiantenergy beam, which comprises:

' a stabilized, bi-channel output amplifier;

a pair of orthogonally oriented electromagnetic deflection coils fordeflecting said beam, said coils being connected to'the respectiveoutput terminal of said bi-channel amplifier; and p at least onegenerator having is output terminal connected to the input ten'ninal ofsaid bi-channel amplifier, said at least one generator including:

a first operational amplifier;

a first integrator comprising a second operational amplifier, a firstplurality of capacitors and first switching means for selectivelyconnecting one of said first plurality of capacitors as a feedbackconnection from the output of said second operational amplifier to theinput thereof;

a second integrator comprising a third operational amplifier, a secondplurality of capacitors and second switching means, ganged mechanicallyto said first switching means, for selectively connecting one of saidsecond plurality of capacitors as a feedback connection from the outputof said third operational amplifier to the input thereof;

a first analog multiplier having two inputs and an output,

the output being connected to the input of said first integrator, andone input of said analog multiplier being connected to the output ofsaid first operational amplifier;

a second analog multiplier having two inputs and an output, thelast-mentioned output being connected to the input of said secondintegrator, and one input of said second analog multiplier beingconnected to the output of said first integrator;

a fourth voltage divider connected between ground and the d.c. sourcefor said generator;

an adder circuit having an output and two inputs, the output of saidadder circuit being connected to the other inputs of both said first andsaid second analog multipliers, one input of said adder circuit beingconnected to ground, the other input of said adder circuit beingconnected to the center tap of said fourth voltage divider;

means, also connected to the other input of said adder circuit, forsupplying an external frequency modulating signal to said generator;

means for connecting the output of said second integrator to the inputof said first operational amplifier to form a closed, oscillatory loop,the coarse adjustment of the frequency of oscillation thereof beingefiected by said first and second switching means, and fine adjustmentof said frequency being effected by said fourth voltage divider, theoutput signal of said at least one generator having a sinusoidal waveform, modulated by said modulating signal, and deriving from the outputof said first integrator, the output of said second integrator yieldinga second output signal, in modulated, cosinusoidal wave form.

4. The apparatus according to claim 3, further comprising:

third and fourth analog multipliers, each having an output and twoinputs, the outputs of said first and second integrators beingconnected, via equal second and third resistors, to the first and secondinputs, respectively, of said bi-channel amplifier and to one input ofeach of said third and fourth analog multipliers, the outputs of saidthird and fourth analog multipliers being connected, via fourth andfifth identical resistors, to the first and second inputs, respectively,of said bi-channel amplifier; and

means, connected simultaneously, to the other inputs of said third andfourth analog multipliers, for supplying an external source of amplitudemodulating signals.

5. Apparatus for controllably deflecting a radiant energy beam, whichcomprises:

a stabilized, bi-channel output amplifier;

a pair of orthogonally oriented electromagnetic deflection coils fordeflecting said beam, said coils being connected to the respectiveoutput terminals of said bi-channel amplifier; and

at least one generator having its output temiinal connected to the inputterminal of said bi-channel amplifier, said at least one generatorincluding:

an inverting, integrating stage including a fourth operationalamplifier, a plurality of capacitors, and third switching means forselectively connecting one of said plurality of capacitors as a feedbackconnection between the output and the input of said fourth operationalamplifier;

a hysteresis switching circuit connected to the output of saidintegrating stage;

a pulse shaping circuit connected to the output of said hysteresisswitching circuit; and

a fifth voltage divider connected between ground and the amplifiedoutput of said pulse shaping circuit, the center tap of said fifthvoltage divider being connected to an input of said integrating stage,the connection completing a closed oscillatory loop, the frequency ofoscillation being coarsely determined by said third switching means andfinely by said fifth voltage divider, the output signal of said at leastone generator having a triangular wave form and deriving from the outputof said integrating stage, the amplified output of said pulse shapingcircuit yielding a second output signal, rectangular in wave fonn.

6. Apparatus for controllably deflecting a radiant energy beam, whichcomprises:

a stabilized, bi-channel output amplifier;

a pair of orthogonally oriented electromagnetic deflection coils fordeflecting said beam, said coils being connected to the respectiveoutput terminals of said bi-channel amplifier; and

at least one generator having its output terminal connected to the inputterminal of said bi-channel amplifier, said at least one generatorincluding:

an inverting, integrating stage including a fourth operationalamplifier, a plurality of capacitors, and third switching means forselectively connecting one of said plurality of capacitors as a feedbackconnection between the output and the input of said fourth operationalamplifier;

a hysteresis switching circuit connected to the output of saidintegrating stage;

a pulse shaping circuit connected to the output of said hysteresisswitching circuit;

a third analog multiplier stage having two inputs and an output, theoutput being connected to the input of said inverting, integratingcircuit, sand one input thereof being connected to the amplified outputof said pulse shaping circuit;

a sixth voltage divider connected between ground and the dc. source forsaid generator;

an adder circuit having an output and two inputs, the output thereofbeing connected to the other input of said third analog multiplier, oneinput of said adder circuit being connected to ground, the other inputof said adder circuit being connected to the center tap of said sixthvoltage divider;

means, also connected to the other input of said adder circuit, forsupplying an external frequency modulating signal to said generator;

said adder circuit and third analog multiplier stage completing aclosed, oscillatory loop, the coarse adjustment of the frequent; ofoscillation thereof being effected b said d swr c g means and fine adustment being e ected by said sixth voltage divider, the output signalof said at least one generator being triangular in wave form, modulatedby said modulating signal, the output of said pulse shaping circuityielding a second output signal in modulated, rectangular form.

7. The apparatus according to claim 5, further comprising:

fifth and sixth analog multipliers each having an output and two inputs,the outputs of said integrating stage and said pulse shaping stage beingconnected, via equal sixth and seventh resistors, to the first andsecond inputs, respectively, of said bi-channel amplifier and to oneinput of said fifth and sixth analog multipliers, respectively, theoutput of said fifth and sixth analog multipliers being connected byeighth and ninth identical resistors, to the first and second inputs,respectively, of said bi-channel amplifier; and

means, connected simultaneously, to the other inputs of said fifth andsixth analog multipliers, for supplying an external source of amplitudemodulating signals.

III k t

1. Apparatus for controllably deflecting a radiant energy beam, whichcomprises: a stabilized, bi-channel output amplifier; a pair oforthogonally oriented electromagnetic deflection coils for deflectingsaid beam, said coils being connected to the respective output terminalof said bi-channel amplifier; and at least one generator having itsoutput terminal connected to the input terminal of said bi-channelamplifier, said at least one generator including: a first operationalamplifier; a first integrator comprising a second operational amplifier,a first plurality of capacitors and first switching means forselectively connecting one of said first plurality of capacitors as afeedback connection from the output of said second operational amplifierto the input thereof; a second integrator comprising a third operationalamplifier, a second plurality of capacitors and second switching means,ganged mechanically to said first switching means, for selectivelyconnecting one of said second plurality of Capacitors as a feedbackconnection from the output of said third operational amplifier to theinput thereof; a first voltage divider connected between the output ofsaid first operational amplifier and ground, the center tap of saidvoltage divider being connected to the input of said first integrator; asecond voltage divider, mechanically ganged to said first voltagedivider, connected between the output of said first integrator andground, the center tap of said second voltage divider being connected tothe input of said second integrator; means for connecting the output ofsaid second integrator to the input of said first operational amplifierto form a closed, oscillatory loop, coarse adjustment of the frequencyof oscillation thereof being effected by said first and second switchingmeans, and fine adjustment thereof by said first and second voltagedividers, the output signal of said at least one generator having asinusoidal wave form and deriving from the output of said firstintegrator, the output of said second integrator yielding a secondoutput signal, co-sinusoidal in wave form.
 2. The deflecting apparatusaccording to claim 1, further comprising: a resistor and a capacitor,serially connected between ground and the d.c. supply for saidgenerator, to form an R-C timing circuit; a transistor in common emitterconfiguration with its emitter connected to ground, its collectorconnected to said d.c. source, and its base connected to the juncture ofsaid resistor and said capacitor; a third voltage divider connectedbetween said d.c. source and ground; and a relay having its armatureconnected in the collector circuit of said transistor and a normallyopen pair of relay contacts connecting the center tap of said thirdvoltage divider to the particular one of said first plurality ofcapacitors selected by said first switching means, whereby as saidserially connected capacitor charges through said resistor, saidtransistor is biassed into conduction thereby operating said relay andcharging said selected capacitor through said pair of relay contacts. 3.Apparatus for controllably deflecting a radiant energy beam, whichcomprises: a stabilized, bi-channel output amplifier; a pair oforthogonally oriented electromagnetic deflection coils for deflectingsaid beam, said coils being connected to the respective output terminalof said bi-channel amplifier; and at least one generator having itsoutput terminal connected to the input terminal of said bi-channelamplifier, said at least one generator including: a first operationalamplifier; a first integrator comprising a second operational amplifier,a first plurality of capacitors and first switching means forselectively connecting one of said first plurality of capacitors as afeedback connection from the output of said second operational amplifierto the input thereof; a second integrator comprising a third operationalamplifier, a second plurality of capacitors and second switching means,ganged mechanically to said first switching means, for selectivelyconnecting one of said second plurality of capacitors as a feedbackconnection from the output of said third operational amplifier to theinput thereof; a first analog multiplier having two inputs and anoutput, the output being connected to the input of said firstintegrator, and one input of said analog multiplier being connected tothe output of said first operational amplifier; a second analogmultiplier having two inputs and an output, the last-mentioned outputbeing connected to the input of said second integrator, and one input ofsaid second analog multiplier being connected to the output of saidfirst integrator; a fourth voltage divider connected between ground andthe d.c. source for said generator; an adder circuit having an outputand two inputs, the output of said adder circuit being connected to theother inputs of both said first and said second analog multipliers, oneinput of said adder circuit being connected to ground, the other inputof said adder circuit being connected to the center tap of said fourthvoltage divider; means, also connected to the other input of said addercircuit, for supplying an external frequency modulating signal to saidgenerator; means for connecting the output of said second integrator tothe input of said first operational amplifier to form a closed,oscillatory loop, the coarse adjustment of the frequency of oscillationthereof being effected by said first and second switching means, andfine adjustment of said frequency being effected by said fourth voltagedivider, the output signal of said at least one generator having asinusoidal wave form, modulated by said modulating signal, and derivingfrom the output of said first integrator, the output of said secondintegrator yielding a second output signal, in modulated, co-sinusoidalwave form.
 4. The apparatus according to claim 3, further comprising:third and fourth analog multipliers, each having an output and twoinputs, the outputs of said first and second integrators beingconnected, via equal second and third resistors, to the first and secondinputs, respectively, of said bi-channel amplifier and to one input ofeach of said third and fourth analog multipliers, the outputs of saidthird and fourth analog multipliers being connected, via fourth andfifth identical resistors, to the first and second inputs, respectively,of said bi-channel amplifier; and means, connected simultaneously, tothe other inputs of said third and fourth analog multipliers, forsupplying an external source of amplitude modulating signals. 5.Apparatus for controllably deflecting a radiant energy beam, whichcomprises: a stabilized, bi-channel output amplifier; a pair oforthogonally oriented electromagnetic deflection coils for deflectingsaid beam, said coils being connected to the respective output terminalsof said bi-channel amplifier; and at least one generator having itsoutput terminal connected to the input terminal of said bi-channelamplifier, said at least one generator including: an inverting,integrating stage including a fourth operational amplifier, a pluralityof capacitors, and third switching means for selectively connecting oneof said plurality of capacitors as a feedback connection between theoutput and the input of said fourth operational amplifier; a hysteresisswitching circuit connected to the output of said integrating stage; apulse shaping circuit connected to the output of said hysteresisswitching circuit; and a fifth voltage divider connected between groundand the amplified output of said pulse shaping circuit, the center tapof said fifth voltage divider being connected to an input of saidintegrating stage, the connection completing a closed oscillatory loop,the frequency of oscillation being coarsely determined by said thirdswitching means and finely by said fifth voltage divider, the outputsignal of said at least one generator having a triangular wave form andderiving from the output of said integrating stage, the amplified outputof said pulse shaping circuit yielding a second output signal,rectangular in wave form.
 6. Apparatus for controllably deflecting aradiant energy beam, which comprises: a stabilized, bi-channel outputamplifier; a pair of orthogonally oriented electromagnetic deflectioncoils for deflecting said beam, said coils being connected to therespective output terminals of said bi-channel amplifier; and at leastone generator having its output terminal connected to the input terminalof said bi-channel amplifier, said at least one generator including: aninverting, integrating stage including a fourth operational amplifier, aplurality of capacitors, and third switching means for selectivelyconnecting one of said plurality of capacitors as a feedback connectionbetween the output and the input of said fourth operational amplifiEr; ahysteresis switching circuit connected to the output of said integratingstage; a pulse shaping circuit connected to the output of saidhysteresis switching circuit; a third analog multiplier stage having twoinputs and an output, the output being connected to the input of saidinverting, integrating circuit, sand one input thereof being connectedto the amplified output of said pulse shaping circuit; a sixth voltagedivider connected between ground and the d.c. source for said generator;an adder circuit having an output and two inputs, the output thereofbeing connected to the other input of said third analog multiplier, oneinput of said adder circuit being connected to ground, the other inputof said adder circuit being connected to the center tap of said sixthvoltage divider; means, also connected to the other input of said addercircuit, for supplying an external frequency modulating signal to saidgenerator; said adder circuit and third analog multiplier stagecompleting a closed, oscillatory loop, the coarse adjustment of thefrequency of oscillation thereof being effected by said third switchingmeans and fine adjustment being effected by said sixth voltage divider,the output signal of said at least one generator being triangular inwave form, modulated by said modulating signal, the output of said pulseshaping circuit yielding a second output signal in modulated,rectangular form.
 7. The apparatus according to claim 5, furthercomprising: fifth and sixth analog multipliers each having an output andtwo inputs, the outputs of said integrating stage and said pulse shapingstage being connected, via equal sixth and seventh resistors, to thefirst and second inputs, respectively, of said bi-channel amplifier andto one input of said fifth and sixth analog multipliers, respectively,the output of said fifth and sixth analog multipliers being connected byeighth and ninth identical resistors, to the first and second inputs,respectively, of said bi-channel amplifier; and means, connectedsimultaneously, to the other inputs of said fifth and sixth analogmultipliers, for supplying an external source of amplitude modulatingsignals.